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// Copyright 2017 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <algorithm>
#include <chrono>
#include <mutex>
#include <thread>
#include "common/math_util.h"
#include "core/perf_stats.h"
#include "core/settings.h"
using namespace std::chrono_literals;
using DoubleSecs = std::chrono::duration<double, std::chrono::seconds::period>;
using std::chrono::duration_cast;
using std::chrono::microseconds;
namespace Core {
void PerfStats::BeginSystemFrame() {
std::lock_guard<std::mutex> lock(object_mutex);
frame_begin = Clock::now();
}
void PerfStats::EndSystemFrame() {
std::lock_guard<std::mutex> lock(object_mutex);
auto frame_end = Clock::now();
accumulated_frametime += frame_end - frame_begin;
system_frames += 1;
previous_frame_length = frame_end - previous_frame_end;
previous_frame_end = frame_end;
}
void PerfStats::EndGameFrame() {
std::lock_guard<std::mutex> lock(object_mutex);
game_frames += 1;
}
PerfStats::Results PerfStats::GetAndResetStats(microseconds current_system_time_us) {
std::lock_guard<std::mutex> lock(object_mutex);
const auto now = Clock::now();
// Walltime elapsed since stats were reset
const auto interval = duration_cast<DoubleSecs>(now - reset_point).count();
const auto system_us_per_second = (current_system_time_us - reset_point_system_us) / interval;
Results results{};
results.system_fps = static_cast<double>(system_frames) / interval;
results.game_fps = static_cast<double>(game_frames) / interval;
results.frametime = duration_cast<DoubleSecs>(accumulated_frametime).count() /
static_cast<double>(system_frames);
results.emulation_speed = system_us_per_second.count() / 1'000'000.0;
// Reset counters
reset_point = now;
reset_point_system_us = current_system_time_us;
accumulated_frametime = Clock::duration::zero();
system_frames = 0;
game_frames = 0;
return results;
}
double PerfStats::GetLastFrameTimeScale() {
std::lock_guard<std::mutex> lock(object_mutex);
constexpr double FRAME_LENGTH = 1.0 / 60;
return duration_cast<DoubleSecs>(previous_frame_length).count() / FRAME_LENGTH;
}
void FrameLimiter::DoFrameLimiting(microseconds current_system_time_us) {
// Max lag caused by slow frames. Can be adjusted to compensate for too many slow frames. Higher
// values increase the time needed to recover and limit framerate again after spikes.
constexpr microseconds MAX_LAG_TIME_US = 25us;
if (!Settings::values.use_frame_limit) {
return;
}
auto now = Clock::now();
const double sleep_scale = Settings::values.frame_limit / 100.0;
// Max lag caused by slow frames. Shouldn't be more than the length of a frame at the current
// speed percent or it will clamp too much and prevent this from properly limiting to that
// percent. High values means it'll take longer after a slow frame to recover and start
// limiting
const microseconds max_lag_time_us = duration_cast<microseconds>(
std::chrono::duration<double, std::chrono::microseconds::period>(25ms / sleep_scale));
frame_limiting_delta_err += duration_cast<microseconds>(
std::chrono::duration<double, std::chrono::microseconds::period>(
(current_system_time_us - previous_system_time_us) / sleep_scale));
frame_limiting_delta_err -= duration_cast<microseconds>(now - previous_walltime);
frame_limiting_delta_err =
std::clamp(frame_limiting_delta_err, -max_lag_time_us, max_lag_time_us);
if (frame_limiting_delta_err > microseconds::zero()) {
std::this_thread::sleep_for(frame_limiting_delta_err);
auto now_after_sleep = Clock::now();
frame_limiting_delta_err -= duration_cast<microseconds>(now_after_sleep - now);
now = now_after_sleep;
}
previous_system_time_us = current_system_time_us;
previous_walltime = now;
}
} // namespace Core
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